MSHA - Code of Federal Regulations - 30 CFR 75.820
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MSHA -  Title 30 CFR

30 CFR § 75.820
Electrical work; troubleshooting and testing.


     (a) Electrical work on all circuits and equipment associated with high-voltage longwalls must be performed only by persons qualified under § 75.153 to perform electrical work on all circuits and equipment.
     (b) Prior to performing electrical work, except for troubleshooting and testing of energized circuits and equipment as provided for in paragraph (d) of this section, a qualified person must do the following:
     (1) Deenergize the circuit or equipment with a circuit-interrupting device.
     (2) Open the circuit disconnecting device. On high-voltage circuits, ground the power conductors until work on the circuit is completed.
     (3) Lock out the disconnecting device with a padlock. When more than one qualified person is performing work, each person must install an individual padlock.
     (4) Tag the disconnecting device to identify each person working and the circuit or equipment on which work is being performed.
     (c) Each padlock and tag must be removed only by the person who installed them, except that, if that person is unavailable at the mine, the lock and tag may be removed by a person authorized by the operator, provided--
     (1) The authorized person is qualified under paragraph (a) of this section; and
     (2) The operator ensures that the person who installed the lock and tag is aware of the removal before that person resumes work on the affected circuit or equipment.
     (d) Troubleshooting and testing of energized circuits must be performed only--
     (1) On low- and medium-voltage circuits;
     (2) When the purpose of troubleshooting and testing is to determine voltages and currents; and
     (3) By persons qualified to perform electrical work and who wear protective gloves on circuits that exceed 40 volts in accordance with the following table:

------------------------------------------------------------------------
              Circuit voltage                  Type of glove required
------------------------------------------------------------------------
Greater than 120 volts (nominal) (not       Rubber insulating gloves
 intrinsically safe).                        with leather protectors.
40 volts to 120 volts (nominal) (both       Either rubber insulating
 intrinsically safe and non-intrinsically    gloves with leather
 safe).                                      protectors or dry work
                                             gloves.
Greater than 120 volts (nominal)            Either rubber insulating
 (intrinsically safe).                       gloves with leather
                                             protectors or dry work
                                             gloves.
------------------------------------------------------------------------

     (4) Rubber insulating gloves must be rated at least for the nominal voltage of the circuit when the voltage of the circuit exceeds 120 volts nominal and is not intrinsically safe.
     (e) Before troubleshooting and testing a low- or medium-voltage circuit contained in a compartment with a high-voltage circuit, the high-voltage circuit must be deenergized, disconnected, grounded, locked out and tagged in accordance with paragraph (b) of this section.
     (f) Prior to the installation or removal of conveyor belt structure, high-voltage cables extending from the section power center to longwall equipment and located in the belt entries must be:
     (1) Deenergized; or
     (2) Guarded in accordance with § 75.816 of this part, at the location where the belt structure is being installed or removed; or
     (3) Located at least 6.5 feet above the mine floor.